Optical imaging system

ABSTRACT

An optical imaging system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens, sequentially arranged from an object side optical imaging system, and a refractive index of at least one of the lenses is 1.67 or greater.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 USC 119(a) of Korean PatentApplication No. 10-2018-0172452 filed on Dec. 28, 2018 and Korean PatentApplication No. 10-2019-0055679 filed on May 13, 2019 in the KoreanIntellectual Property Office, the entire disclosures of which areincorporated herein by reference for all purposes.

BACKGROUND 1. Field

The following description relates to an optical imaging system.

2. Description of Background

Mobile communications terminals have been provided with camera modules,enabling video calling and image capturing. In addition, as levels offunctionality of cameras in such mobile communications terminals havegradually increased, cameras for use in mobile communications terminalshave gradually been required to have higher levels of resolution andperformance.

However, since there is a trend for mobile communications terminals tobe gradually miniaturized and lightened, there are limitations inrealizing camera modules having high resolution and performance.

In order to solve such problems, recent camera lenses have been formedof plastic, a material lighter than glass, and optical imaging systemshave been configured of five or six lenses to implement a high level ofresolution.

SUMMARY

This Summary is provided to introduce a selection of concepts insimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

An optical imaging system capable of improving an aberration improvementeffect and implementing high resolution.

In one general aspect, an optical imaging system includes a first lens,a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens,a seventh lens, and an eighth lens sequentially arranged from an objectside of the optical imaging system, and a refractive index of at leastone of the lenses is 1.67 or greater.

The optical imaging system may satisfy FOV>70°, where FOV is a field ofview of an imaging system including the first lens to the eighth lens.

The optical imaging system may satisfy f/EPD<1.9, where f is an overallfocal length of an imaging system including the first lens to the eighthlens, and EPD is a diameter of an entrance pupil.

The first lens may have positive refractive power, the second lens mayhave positive refractive power, and the third lens may have positiverefractive power.

The fourth lens may have negative refractive power, the fifth lens mayhave positive refractive power, the sixth lens may have negativerefractive power, the seventh lens may have positive refractive power,and the eighth lens may have negative refractive power.

The first lens may have negative refractive power, the second lens mayhave positive refractive power, and the third lens may have positiverefractive power.

The fourth lens may have negative refractive power, the fifth lens mayhave positive refractive power, the sixth lens may have positiverefractive power, the seventh lens may have positive refractive power,and the eighth lens may have negative refractive power.

The first lens may have positive refractive power, the second lens mayhave negative refractive power, and the third lens may have positiverefractive power.

The fourth lens may have negative refractive power, the fifth lens mayhave positive refractive power, the sixth lens may have positiverefractive power, the seventh lens may have negative refractive power,and the eighth lens may have negative refractive power.

The optical imaging system may include a stop disposed between the firstlens and the second lens.

Among the lenses, an absolute value of a focal length of the eighth lensmay be the lowest.

At least one of the lenses may have positive refractive power with arefractive index of 1.67 or greater, and at least one of the lenses mayhave negative refractive power with a refractive index of 1.65 orgreater.

In another general aspect, an optical imaging system includes: a firstlens, a second lens, a third lens, a fourth lens, a fifth lens, a sixthlens, a seventh lens, and an eighth lens sequentially arranged from anobject side of the optical imaging system, an object-side surface of thefirst lens is convex, an image-side surface of the first lens isconcave, a refractive index of at least one of the lenses is 1.67 orgreater, and Fno<1.9, where Fno is an F-number of an imaging systemincluding the first lens to the eighth lens.

At least one of the lenses may have positive refractive power with arefractive index of 1.67 or greater, and at least one of the lenses mayhave negative refractive power with a refractive index of 1.65 orgreater.

The optical imaging system may satisfy FOV>70°, where FOV is a field ofview of an imaging system including the first lens to the eighth lens.

The optical imaging system may satisfy TTL/(2*IMG HT)<0.9, where TTL isan optical axis distance from the object-side surface of the first lensto an image capturing surface of an image sensor, and IMG HT is half ofa diagonal length of the image capturing surface of the image sensor.

In another general aspect, an optical imaging system includes: a firstlens, a second lens, a third lens, a fourth lens, a fifth lens, a sixthlens, a seventh lens, and an eighth lens sequentially arranged from anobject side of the optical imaging system, and f/EPD<1.9, where f is anoverall focal length of an imaging system including the first lens tothe eighth lens and EPD is a diameter of an entrance pupil.

At least four of the lenses may have positive refractive power.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view illustrating an optical imaging system according to afirst example.

FIG. 2 is a view illustrating aberration characteristics of the opticalimaging system illustrated in FIG. 1.

FIG. 3 is a view illustrating an optical imaging system according to asecond example.

FIG. 4 is a view illustrating aberration characteristics of the opticalimaging system illustrated in FIG. 3.

FIG. 5 is a view illustrating an optical imaging system according to athird example.

FIG. 6 is a view illustrating aberration characteristics of the opticalimaging system illustrated in FIG. 5.

FIG. 7 is a view illustrating an optical imaging system according to afourth example.

FIG. 8 is a view illustrating aberration characteristics of the opticalimaging system illustrated in FIG. 7.

FIG. 9 is a view illustrating an optical imaging system according to afifth example.

FIG. 10 is a view illustrating aberration characteristics of the opticalimaging system illustrated in FIG. 9.

Throughout the drawings and the detailed description, the same referencenumerals refer to the same elements. The drawings may not be to scale,and the relative size, proportions, and depiction of elements in thedrawings may be exaggerated for clarity, illustration, and convenience.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses,and/or systems described herein. However, various changes,modifications, and equivalents of the methods, apparatuses, and/orsystems described herein will be apparent to one of ordinary skill inthe art. The sequences of operations described herein are merelyexamples, and are not limited to those set forth herein, but may bechanged as will be apparent to one of ordinary skill in the art, withthe exception of operations necessarily occurring in a certain order.Also, descriptions of functions and constructions that would be wellknown to one of ordinary skill in the art may be omitted for increasedclarity and conciseness.

The features described herein may be embodied in different forms, andare not to be construed as being limited to the examples describedherein. Rather, the examples described herein have been provided so thatthis disclosure will be thorough and complete, and will fully convey thescope of the disclosure to one of ordinary skill in the art.

Herein, it is noted that use of the term “may” with respect to anexample or embodiment, e.g., as to what an example or embodiment mayinclude or implement, means that at least one example or embodimentexists in which such a feature is included or implemented while allexamples and embodiments are not limited thereto.

Throughout the specification, when an element, such as a layer, region,or substrate, is described as being “on,” “connected to,” or “coupledto” another element, it may be directly “on,” “connected to,” or“coupled to” the other element, or there may be one or more otherelements intervening therebetween. In contrast, when an element isdescribed as being “directly on,” “directly connected to,” or “directlycoupled to” another element, there can be no other elements interveningtherebetween.

As used herein, the term “and/or” includes any one and any combinationof any two or more of the associated listed items.

Although terms such as “first,” “second,” and “third” may be used hereinto describe various members, components, regions, layers, or sections,these members, components, regions, layers, or sections are not to belimited by these terms. Rather, these terms are only used to distinguishone member, component, region, layer, or section from another member,component, region, layer, or section. Thus, a first member, component,region, layer, or section referred to in examples described herein mayalso be referred to as a second member, component, region, layer, orsection without departing from the teachings of the examples.

Spatially relative terms such as “above,” “upper,” “below,” and “lower”may be used herein for ease of description to describe one element'srelationship to another element as shown in the figures. Such spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. For example, if the device in the figures is turned over,an element described as being “above” or “upper” relative to anotherelement will then be “below” or “lower” relative to the other element.Thus, the term “above” encompasses both the above and below orientationsdepending on the spatial orientation of the device. The device may alsobe oriented in other ways (for example, rotated 90 degrees or at otherorientations), and the spatially relative terms used herein are to beinterpreted accordingly.

The terminology used herein is for describing various examples only, andis not to be used to limit the disclosure. The articles “a,” “an,” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. The terms “comprises,” “includes,”and “has” specify the presence of stated features, numbers, operations,members, elements, and/or combinations thereof, but do not preclude thepresence or addition of one or more other features, numbers, operations,members, elements, and/or combinations thereof.

Due to manufacturing techniques and/or tolerances, variations of theshapes shown in the drawings may occur. Thus, the examples describedherein are not limited to the specific shapes shown in the drawings, butinclude changes in shape that occur during manufacturing.

The features of the examples described herein may be combined in variousways as will be apparent after an understanding of the disclosure ofthis application. Further, although the examples described herein have avariety of configurations, other configurations are possible as will beapparent after an understanding of the disclosure of this application.

In the drawings, the thicknesses, sizes, and shapes of lenses aresomewhat exaggerated for convenience of explanation. In particular, theshapes of spherical surfaces or aspherical surfaces illustrated in thedrawings are only illustrative. That is, the shapes of the sphericalsurfaces or the aspherical surfaces are not limited to those illustratedin the drawings.

Herein, a first lens refers to a lens closest to an object, while aneighth lens refers to a lens closest to an image sensor.

A first surface of each lens refers to a surface thereof closest to anobject side (or an object-side surface) and a second surface of eachlens refers to a surface thereof closest to an image side (or animage-side surface). Further, all numerical values of radii of curvatureand thicknesses or distances of lenses, and the like, are indicated bymillimeters (mm), and a field of view (FOV) is indicated by degrees.

Further, in a description for a shape of each of the lenses, the meaningthat one surface of a lens is convex is that a paraxial region portionof a corresponding surface is convex, and the meaning that one surfaceof a lens is concave is that a paraxial region portion of acorresponding surface is concave. Thus, even when it is described thatone surface of a lens is convex, an edge portion of the lens may beconcave. In a similar manner, even when it is described that one surfaceof a lens is concave, an edge portion of the lens may be convex.

A paraxial region refers to a very narrow region including an opticalaxis.

An optical imaging system according to various examples may includeeight lenses.

For example, the optical imaging system may include a first lens, asecond lens, a third lens, a fourth lens, a fifth lens, a sixth lens, aseventh lens, and an eighth lens, sequentially arranged from the objectside. The first lens to the eighth lens are respectively spaced apartfrom each other by a predetermined distance along the optical axis.

However, the optical imaging system is not limited to only includingeight lenses, but may further include other components, when necessary.

For example, the optical imaging system may further include an imagesensor converting an image of a subject incident on the image sensorinto an electrical signal.

The optical imaging system may further include an infrared filter(hereinafter, ‘filter’) cutting off infrared light. The filter may bedisposed between the eighth lens and the image sensor.

The optical imaging system may further include a stop controlling anamount of light.

In the optical imaging system, the first to eighth lenses may be formedof plastic.

At least one of the first to eighth lenses may have an asphericalsurface. Further, each of the first to eighth lenses may have at leastone aspherical surface.

At least one of first and second surfaces of all of the first to eighthlenses may be aspherical. The aspherical surfaces of the first to eighthlenses may be represented by the following Equation 1:

$\begin{matrix}{Z = {\frac{{cY}^{2}}{1 + \sqrt{1 - {\left( {1 + K} \right)c^{2}Y^{2}}}} + {AY}^{4} + {BY}^{6} + {CY}^{8} + {DY}^{10} + {EY}^{12} + {FY}^{14} + {GY}^{16} + {HY}^{18} + {{IY}^{20}\mspace{14mu} \ldots}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

In Equation 1, c is a curvature (an inverse of a radius of curvature) ofa lens, K is a conic constant, and Y is a distance from a certain pointon an aspherical surface of the lens to an optical axis. In addition,constants A to I are aspherical coefficients. In addition, Z is adistance from the certain point on the aspherical surface of the lens toa tangential plane meeting the apex of the aspherical surface of thelens.

The optical imaging system including the first to eighth lenses may havepositive refractive power/positive refractive power/positive refractivepower/negative refractive power/positive refractive power/negativerefractive power/positive refractive power/negative refractive powersequentially from the object side. Alternatively, the first to eighthlenses may have negative refractive power/positive refractivepower/positive refractive power/negative refractive power/positiverefractive power/positive refractive power/positive refractivepower/negative refractive power. Alternatively, the first to eighthlenses may have positive refractive power/negative refractivepower/positive refractive power/negative refractive power/positiverefractive power/positive refractive power/negative refractivepower/negative refractive power.

The optical imaging system according to various examples may satisfy thefollowing Conditional Expressions:

Conditional Expression 1: f/EPD<1.9

Conditional Expression 2: FOV>70° Conditional Expression 3: TTL/(2*IMGHT)<0.9

In the Conditional Expressions, f is an overall focal length of theoptical imaging system, EPD is a diameter of entrance pupil, FOV is afield of view of the optical imaging system, TTL is an optical axisdistance from the object-side surface of the first lens to an imagecapturing surface of the image sensor, and IMG HT is half of a diagonallength of the image capturing surface of the image sensor.

In the Conditional Expressions, f/EPD is an F number of the opticalimaging system.

The first lens may have positive or negative refractive power. The firstlens may have a meniscus shape of which an object-side surface isconvex. A first surface of the first lens may be convex, and a secondsurface thereof may be concave.

At least one of the first and second surfaces of the first lens may beaspherical. For example, both surfaces of the first lens may beaspherical.

The second lens may have positive or negative refractive power. Bothsurfaces of the second lens may be convex. For example, first and secondsurfaces of the second lens may be convex.

Alternatively, the second lens may have a meniscus shape of which anobject-side surface is convex. For example, a first surface of thesecond lens may be convex, and a second surface thereof may be concave.

At least one of the first and second surfaces of the second lens may beaspherical. For example, both surfaces of the second lens may beaspherical.

The third lens may have positive refractive power. Both surfaces of thethird lens may be convex. For example, first and second surfaces of thethird lens may be convex.

Alternatively, the third lens may have a meniscus shape of which anobject-side surface is convex. For example, a first surface of the thirdlens may be convex in a paraxial region, and a second surface thereofmay be concave in the paraxial region.

At least one of the first and second surfaces of the third lens may beaspherical. For example, both surfaces of the third lens may beaspherical.

At least one inflection point may be formed on at least one of the firstand second surfaces of the third lens. For example, the first surface ofthe third lens may be convex in a paraxial region and become concavetoward an edge thereof.

The fourth lens may have negative refractive power. The fourth lens mayhave a meniscus shape of which an object-side surface is convex. Forexample, a first surface of the fourth lens may be convex in a paraxialregion, and a second surface thereof may be concave in the paraxialregion.

At least one of the first and second surfaces of the fourth lens may beaspherical. For example, both surfaces of the fourth lens may beaspherical.

At least one inflection point may be formed on at least one of the firstand second surfaces of the fourth lens. For example, the first surfaceof the fourth lens may be convex in a paraxial region and become concavetoward an edge thereof. The second surface of the fourth lens may beconcave in the paraxial region and become convex toward an edge thereof.

The fifth lens may have positive refractive power. The fifth lens mayhave a meniscus shape of which an image-side surface is convex. Forexample, a first surface of the fifth lens may be concave, and a secondsurface thereof may be convex.

At least one of the first and second surfaces of the fifth lens may beaspherical. For example, both surfaces of the fifth lens may beaspherical.

The sixth lens may have positive or negative refractive power. The sixthlens may have a meniscus shape of which an object-side surface isconvex. For example, a first surface of the sixth lens may be convex ina paraxial region, and a second surface thereof may be concave in theparaxial region.

Alternatively, the sixth lens may have a meniscus shape of which animage-side surface is convex. For example, a first surface of the sixthlens may be concave in a paraxial region, and a second surface thereofmay be convex in the paraxial region.

At least one of the first and second surfaces of the sixth lens may beaspherical. For example, both surfaces of the sixth lens may beaspherical.

At least one inflection point may be formed on at least one of the firstand second surfaces of the sixth lens. For example, the first surface ofthe sixth lens may be convex in a paraxial region and become concavetoward an edge thereof. The second surface of the sixth lens may beconcave in the paraxial region and become convex toward an edge thereof.

The seventh lens may have positive or negative refractive power. Bothsurfaces of the seventh lens may be convex. For example, first andsecond surfaces of the seventh lens may be convex in the paraxialregion.

Alternatively, the seventh lens may have a meniscus shape of which animage-side surface is convex. For example, a first surface of theseventh lens may be concave in a paraxial region, and a second surfacethereof may be convex in the paraxial region.

At least one of the first and second surfaces of the seventh lens may beaspherical. For example, both surfaces of the seventh lens may beaspherical.

At least one inflection point may be formed on at least one of the firstand second surfaces of the seventh lens. For example, the first surfaceof the seventh lens may be convex in a paraxial region and becomeconcave toward an edge thereof.

The eighth lens may have negative refractive power. The eighth lens mayhave a meniscus shape of which an object-side surface is convex. Forexample, a first surface of the eighth lens may be convex in a paraxialregion, and a second surface thereof may be concave in the paraxialregion.

Alternatively, both surfaces of the eighth lens may be concave. Forexample, first and second surfaces of the eighth lens may be concave ina paraxial region.

At least one of the first and second surfaces of the eighth lens may beaspherical. For example, both surfaces of the eighth lens may beaspherical.

At least one inflection point may be formed on at least one of the firstand second surfaces of the eighth lens. For example, the first surfaceof the eighth lens may be convex in a paraxial region and become concavetoward an edge thereof. The second surface of the eighth lens may beconcave in the paraxial region and become convex toward an edge thereof.

A refractive index of at least one among the first to eighth lenses maybe 1.68 or more.

Among the first to eighth lenses, a refractive index of at least one oflenses having positive refractive power may be 1.67 or more, and arefractive index of at least one of lenses having negative refractivepower may be 1.65 or more.

Among the first lens to the eighth lens, the absolute value of the focallength of the eighth lens is the smallest.

In the optical imaging system configured as described above, a pluralityof lenses may perform an aberration correction function to increaseaberration improvement performance.

An optical imaging system according to a first example is hereinafterdescribed with reference to FIGS. 1 and 2.

The optical imaging system according to the first example may include afirst lens 110, a second lens 120, a third lens 130, a fourth lens 140,a fifth lens 150, a sixth lens 160, a seventh lens 170, and an eighthlens 180, and may further include a stop ST, a filter 190, and an imagesensor 191.

Lens characteristics (radii of curvature, thicknesses of lenses ordistances between the lenses, refractive indices, Abbe numbers, andfocal lengths) of each lens are shown in Table 1.

TABLE 1 Surface Radius of Thickness/ Refractive Abbe Focal No. Ref.Curvature Distance Index Number Length 1 First Lens 5.82064 0.472571.5441 56.1 252.19 2 Stop 5.90293 0.1 3 Second Lens 3.61912 0.641711.5441 56.1 6.54 4 −268.9537 0.156 5 Third Lens 8.30685 0.51871 1.544156.1 9.789 6 −14.69406 0.1 7 Fourth Lens 10.73461 0.28 1.65739 21.5−8.523 8 3.64353 0.50686 9 Fifth Lens −7.98512 0.53435 1.68902 18.41039.77 10 −8.11268 0.28018 11 Sixth Lens 5.02652 0.49861 1.5441 56.1−198.47 12 4.6355 0.38009 13 Seventh Lens 11.03365 0.90765 1.5441 56.18.306 14 −7.48822 0.29126 15 Eighth Lens 9.93959 0.85854 1.5366 55.6−4.708 16 1.95375 0.34196 17 Filter Infinity 0.11 18 Infinity 0.64 19Image Infinity Capturing Surface

According to the first example, an overall focal length of the opticalimaging system f is 5.81 mm, Fno is 1.87, BFL is 1.06 mm, FOV is 78.1°,and IMG HT is 4.7 mm.

Fno is the number indicating the brightness of the optical imagingsystem, BFL is a distance from an image-side surface of the eighth lensto the image capturing surface of the image sensor, FOV is a field ofview of the optical imaging system, and IMG HT is half of a diagonallength of the image capturing surface of the image sensor.

In the first example, the first lens 110 may have positive refractivepower, and a first surface of the first lens 110 may be convex and asecond surface of the first lens 110 may be concave.

The second lens 120 may have positive refractive power, and the firstand second surfaces of the second lens 120 are convex.

The third lens 130 may have positive refractive power, and the first andsecond surfaces of the third lens 130 are convex.

The fourth lens 140 may have negative refractive power, and a firstsurface of the fourth lens 140 may be convex and a second surface of thefourth lens 140 may be concave.

The fifth lens 150 may have positive refractive power, and a firstsurface of the fifth lens 150 may be concave and a second surface of thefifth lens 150 may be convex.

The sixth lens 160 may have negative refractive power, and a firstsurface of the sixth lens 160 may be convex in a paraxial area and asecond surface of the sixth lens 160 may be concave in the paraxialarea.

At least one inflection point may be formed on at least one of the firstand second surfaces of the sixth lens 160. For example, the firstsurface of the sixth lens 160 may be convex in a paraxial region andbecome concave toward an edge thereof. The second surface of the sixthlens 160 may be concave in a paraxial region and become convex toward anedge thereof.

The seventh lens 170 may have positive refractive power, and the firstand second surfaces of the seventh lens 170 are convex in a paraxialarea.

At least one inflection point may be formed on at least one of the firstand second surfaces of the seventh lens 170. For example, the firstsurface of the seventh lens 170 may be convex in a paraxial region andbecome concave toward an edge thereof.

The eighth lens 180 may have negative refractive power, and a firstsurface of the eighth lens 180 may be convex in a paraxial area and asecond surface of the eighth lens 180 may be concave in the paraxialarea.

At least one inflection point may be formed on at least one of the firstand second surfaces of the eighth lens 180. For example, the firstsurface of the eighth lens 180 may be convex in a paraxial region andbecome concave toward an edge thereof. The second surface of the eighthlens 180 may be concave in a paraxial region and become convex toward anedge thereof.

Respective surfaces of the first to eighth lenses 110 to 180 may haveaspherical coefficients as illustrated in Table 2. For example, all ofobject-side surfaces and image-side surfaces of the first to eighthlenses 110 to 180 may be aspherical.

The stop ST may be disposed between the first lens 110 and the secondlens 120.

TABLE 2 1 2 3 4 5 6 7 8 K −3.0581 −2.83302 0.0988 −51.46095 0.14986−5.2952 43.43888 −7.06863 A −0.00838 0.01314 0.02096 0.00324 0.00935−0.01212 −0.04563 −0.00996 B −0.00688 −0.05945 −0.06656 −0.03209−0.03438 0.01148 0.08287 0.05288 C 0.00446 0.06895 0.08698 0.018920.03336 −0.04233 −0.17355 −0.08003 D −0.00009 −0.03853 −0.07421 0.01809−0.007 0.09753 0.2722 0.0851 E −0.00099 0.01212 0.05083 −0.0341 −0.00846−0.11845 −0.27352 −0.05429 F 0.00045 −0.00227 −0.02633 0.02332 0.004660.07798 0.16744 0.01762 G −9.45E−05 0.00025 0.00882 −0.00866 −0.00025−0.02865 −0.06034 −0.0009 H  9.98E−06 −1.54E−05 −0.00163 0.00176−0.00024 0.00558 0.01174 −0.001 I −4.37E−07  3.98E−07 0.00013 −0.000153.48E−05 −0.00045 −0.00095 0.00019 9 10 11 12 13 14 15 16 K 0 −0.175290.37407 −36.08796 1.10E−06 0.0817  −13.89285  −5.58556 A −0.02649−0.02261 −0.01322 0.0579  0.04405 0.03749 −0.0796  −0.03729 B 0.058440.03642 0.01056 −0.05314 −0.03377 −0.0153  0.01971  0.00986 C −0.11232−0.05534 −0.02313 0.02443 0.0119 0.00319 −0.00353  −0.00185 D 0.121640.04431 0.01914 −0.00689 −0.00306 −0.00045  0.00057  0.00023 E −0.07704−0.02009 −0.00877 0.00124  0.00057 4.22E−05 −6.96E−05 −1.97E−05 F0.02637 0.00484 0.0024 −0.00014 −7.15E−05  −2.29E−06   5.64E−06 1.08E−06 G −0.00312 −0.00038 −0.00039 9.96E−06 5.46E−06 5.22E−08−2.81E−07 −3.60E−08 H −0.00057 −6.09E−05  3.57E−05 −3.90E−07  −2.30E−07 3.75E−10  7.81E−09  6.53E−10 I 0.00014  1.00E−05 −1.37E−06 6.50E−094.08E−09 −2.58E−11  −9.23E−11 −4.88E−12

The imaging optical system of FIG. 1 may have the aberrationcharacteristics illustrated in FIG. 2.

An optical imaging system according to a second example is hereinafterdescribed with reference to FIGS. 3 and 4.

The optical imaging system according to the second example may include afirst lens 210, a second lens 220, a third lens 230, a fourth lens 240,a fifth lens 250, a sixth lens 260, a seventh lens 270, and an eighthlens 280, and may further include a stop ST, a filter 290, and an imagesensor 291.

Lens characteristics (radii of curvature, thicknesses of lenses ordistances between the lenses, refractive indices, Abbe numbers, andfocal lengths) of each lens are shown in Table 3.

TABLE 3 Surface Radius of Thickness/ Refractive Abbe Focal No. Ref.Curvature Distance Index Number Length 1 First Lens 5.82349 0.464281.5441 56.1 210.583 2 Stop 5.96107 0.1 3 Second Lens 3.64195 0.679881.5441 56.1 6.704 4 571.89764 0.13167 5 Third Lens 7.95201 0.558181.5441 56.1 9.505 6 −14.61013 0.1 7 Fourth Lens 10.79038 0.3 1.6573921.5 −8.598 8 3.66831 0.45774 9 Fifth Lens −8.0588 0.51534 1.68902 18.43584.996 10 −8.24214 0.24455 11 Sixth Lens 4.9469 0.50197 1.5441 56.1−273.141 12 4.61652 0.37422 13 Seventh Lens 10.91795 0.92002 1.5441 56.18.304 14 −7.53595 0.30118 15 Eighth Lens 10.12587 0.89189 1.5366 55.6−4.763 16 1.97789 0.36 17 Filter Infinity 0.11 18 Infinity 0.52 19 ImageInfinity Capturing Surface

According to the second example, an overall focal length of the opticalimaging system f is 5.65 mm, Fno is 1.79, BFL is 1.00 mm, FOV is 78.1°,and IMG HT is 4.7 mm.

Fno is the number indicating the brightness of the optical imagingsystem, BFL is a distance from an image-side surface of the eighth lensto the image capturing surface of the image sensor, FOV is a field ofview of the optical imaging system, and IMG HT is half of a diagonallength of the image capturing surface of the image sensor.

In the second example, the first lens 210 may have positive refractivepower, and a first surface of the first lens 210 may be convex and asecond surface of the first lens 210 may be concave.

The second lens 220 may have positive refractive power, and a firstsurface of the second lens 220 may be convex and a second surface of thesecond lens 220 may be concave.

The third lens 230 may have positive refractive power, and the first andsecond surfaces of the third lens 230 are convex.

The fourth lens 240 may have negative refractive power, and a firstsurface of the fourth lens 240 may be convex and a second surface of thefourth lens 240 may be concave.

The fifth lens 250 may have positive refractive power, and a firstsurface of the fifth lens 250 may be concave and a second surface of thefifth lens 250 may be convex.

The sixth lens 260 may have negative refractive power, and a firstsurface of the sixth lens 260 may be convex in a paraxial area and asecond surface of the sixth lens 260 may be concave in the paraxialarea.

At least one inflection point may be formed on at least one of the firstand second surfaces of the sixth lens 260. For example, the firstsurface of the sixth lens 260 may be convex in a paraxial region andbecome concave toward an edge thereof. The second surface of the sixthlens 260 may be concave in a paraxial region and become convex toward anedge thereof.

The seventh lens 270 may have positive refractive power, and the firstand second surfaces of the seventh lens 270 are convex in a paraxialarea.

At least one inflection point may be formed on at least one of the firstand second surfaces of the seventh lens 270. For example, the firstsurface of the seventh lens 270 may be convex in a paraxial region andbecome concave toward an edge thereof.

The eighth lens 280 may have negative refractive power, and a firstsurface of the eighth lens 280 may be convex in a paraxial area and asecond surface of the eighth lens 280 may be concave in the paraxialarea.

At least one inflection point may be formed on at least one of the firstand second surfaces of the eighth lens 280. For example, the firstsurface of the eighth lens 280 may be convex in a paraxial region andbecome concave toward an edge thereof. The second surface of the eighthlens 280 may be concave in a paraxial region and become convex toward anedge thereof.

Respective surfaces of the first to eighth lenses 210 to 280 may haveaspherical coefficients as illustrated in Table 4. For example, all ofobject-side surfaces and image-side surfaces of the first to eighthlenses 210 to 280 may be aspherical.

The stop ST may be disposed between the first lens 210 and the secondlens 220.

TABLE 4 1 2 3 4 5 6 7 8 K −2.96193 −2.95518 0.10345 −51.46093 0.32489−5.29525 43.29434 −7.06798 A −0.00808 0.0134 0.01989 0.00326 0.00924−0.00953 −0.04336 −0.01001 B −0.00644 −0.05781 −0.06518 −0.03281−0.03245 −0.00193 0.0721 0.0526 C 0.00357 0.06555 0.08998 0.01904 0.0281−0.00968 −0.14683 −0.07992 D 0.00054 −0.03606 −0.08337 0.02151 0.000310.04793 0.22876 0.08785 E −0.00122 0.0112 0.06068 −0.03953 −0.01461−0.06985 −0.22702 −0.06073 F 0.0005 −0.00208 −0.03191 0.02703 0.007970.04765 0.13586 0.02418 G −1.01E−04 0.00023 0.01059 −0.00997 −0.00135−0.01703 −0.04742 −0.00444 H  1.04E−05 −1.38E−05 −0.00193 0.002 −0.000030.00309 0.00885 −0.00001 I −4.50E−07  3.53E−07 0.00015 −0.00017 1.83E−05−0.00022 −0.00068 0.00008 9 10 11 12 13 14 15 16 K 0.00008 −0.251980.54881 −36.08638 1.10E−04 −0.01972 −13.89277 −5.38036 A −0.02799−0.02393 −0.0126 0.05894 0.04212  0.03228 −0.07811 −0.03512 B 0.06420.04402 0.00834 −0.0554 −0.03097 −0.01066 0.01913  0.00893 C −0.12096−0.06968 −0.02121 0.02604 0.01027  0.00131 −0.0034 −0.00162 D 0.128130.05973 0.01846 −0.00747 −0.00255 −0.00001 0.00054 0.0002 E −0.07878−0.03034 −0.00868 0.00136 0.00048 −1.90E−05 −6.58E−05 −1.70E−05 F0.02529 0.00904 0.00241 −0.00016 −6.07E−05   2.95E−06  5.29E−06 9.49E−07 G −0.00205 −0.00141 −0.0004 1.12E−05 4.71E−06 −2.14E−07−2.62E−07 −3.23E−08 H −0.00091 7.57E−05  3.60E−05 −4.40E−07  −2.01E−07  7.73E−09  7.24E−09  5.97E−10 I 0.00018 2.46E−06 −1.38E−06 7.38E−093.60E−09 −1.11E−10 −8.54E−11 −4.51E−12

The imaging optical system of FIG. 3 may have the aberrationcharacteristics illustrated in FIG. 4.

An optical imaging system according to a third example is hereinafterdescribed with reference to FIGS. 5 and 6.

The optical imaging system according to the third example may include afirst lens 310, a second lens 320, a third lens 330, a fourth lens 340,a fifth lens 350, a sixth lens 360, a seventh lens 370, and an eighthlens 380, and may further include a stop ST, a filter 390, and an imagesensor 391.

Lens characteristics (radii of curvature, thicknesses of lenses ordistances between the lenses, refractive indices, Abbe numbers, andfocal lengths) of each lens are shown in Table 5.

TABLE 5 Surface Radius of Thickness/ Refractive Abbe Focal No. Ref.Curvature Distance Index Number Length 1 First Lens 5.75973 0.261831.5441 56.1 −55.35 2 Stop 4.76071 0.02484 3 Second Lens 3.19735 0.630611.5441 56.1 6.608 4 25.9404 0.24878 5 Third Lens 6.1772 0.57576 1.544156.1 8.144 6 −15.4016 0.02484 7 Fourth Lens 10.67494 0.25241 1.6573921.5 −8.33 8 3.58569 0.4465 9 Fifth Lens −23.06527 0.59589 1.68902 18.4250.721 10 −20.56286 0.52053 11 Sixth Lens 5.21173 0.53754 1.5441 56.132.499 12 7.10739 0.32435 13 Seventh Lens 74.79426 0.83506 1.5441 56.110.867 14 −6.42582 0.39447 15 Eighth Lens 12.65512 0.71108 1.5366 55.6−4.546 16 2.00487 0.31055 17 Filter Infinity 0.11 18 Infinity 0.63 19Image Infinity Capturing Surface

According to the third example, an overall focal length of the opticalimaging system f is 5.90 mm, Fno is 1.88, BFL is 1.06 mm, FOV is 80.5°,and IMG HT is 4.7 mm.

Fno is the number indicating the brightness of the optical imagingsystem, BFL is a distance from an image-side surface of the eighth lensto the image capturing surface of the image sensor, FOV is a field ofview of the optical imaging system, and IMG HT is half of a diagonallength of the image capturing surface of the image sensor.

In the third example, the first lens 310 may have negative refractivepower, and a first surface of the first lens 310 may be convex and asecond surface of the first lens 310 may be concave.

The second lens 320 may have positive refractive power, and a firstsurface of the second lens 320 may be convex and a second surface of thesecond lens 320 may be concave.

The third lens 330 may have positive refractive power, and the first andsecond surfaces of the third lens 330 are convex.

The fourth lens 340 may have negative refractive power, and a firstsurface of the fourth lens 340 may be convex and a second surface of thefourth lens 340 may be concave.

The fifth lens 350 may have positive refractive power, and a firstsurface of the fifth lens 350 may be concave and a second surface of thefifth lens 350 may be convex.

The sixth lens 360 may have negative refractive power, and a firstsurface of the sixth lens 360 may be convex in a paraxial area and asecond surface of the sixth lens 360 may be concave in the paraxialarea.

At least one inflection point may be formed on at least one of the firstand second surfaces of the sixth lens 360. For example, the firstsurface of the sixth lens 360 may be convex in a paraxial region andbecome concave toward an edge thereof. The second surface of the sixthlens 360 may be concave in a paraxial region and become convex toward anedge thereof.

The seventh lens 370 may have positive refractive power, and the firstand second surfaces seventh lens 370 are convex in a paraxial area.

At least one inflection point may be formed on at least one of the firstand second surfaces of the seventh lens 370. For example, the firstsurface of the seventh lens 370 may be convex in a paraxial region andbecome concave toward an edge thereof.

The eighth lens 380 may have negative refractive power, and a firstsurface of the eighth lens 380 may be convex in a paraxial area and asecond surface of the eighth lens 380 may be concave in the paraxialarea.

At least one inflection point may be formed on at least one of the firstand second surfaces of the eighth lens 380. For example, the firstsurface of the eighth lens 380 may be convex in a paraxial region andbecome concave toward an edge thereof. The second surface of the eighthlens 380 may be concave in a paraxial region and become convex toward anedge thereof.

Respective surfaces of the first to eighth lenses 310 to 380 may haveaspherical coefficients as illustrated in Table 6. For example, all ofobject-side surfaces and image-side surfaces of the first to eighthlenses 310 to 380 may be aspherical.

The stop ST may be disposed between the first lens 310 and the secondlens 320.

TABLE 6 1 2 3 4 5 6 7 8 K −3.0854 −2.80283 −0.07155 −51.46095 −0.14705−5.2952 43.78514 −7.18083 A −0.00913 0.02695 0.03284 −0.00717 −0.00518−0.03286 −0.05132 0.01168 B −0.01044 −0.08981 −0.08892 −0.01161 −0.00120.05865 0.06476 −0.06429 C 0.00977 0.09892 0.09968 0.03444 0.01975−0.02766 −0.02608 0.22712 D −0.00272 −0.05411 −0.06072 −0.05929 −0.04472−0.05556 −0.05865 −0.41416 E −0.00041 0.0168 0.02213 0.06011 0.051330.09394 0.10598 0.46735 F 0.00043 −0.00311 −0.00496 −0.03586 −0.0344−0.0675 −0.08423 −0.33181 G −1.05E−04 0.00034 0.00067 0.01239 0.013210.02665 0.03736 0.14407 H  1.18E−05 −2.06E−05  −5.04E−05 −0.00227−0.00265 −0.00557 −0.00887 −0.03489 I −5.10E−07 5.22E−07 0 0.000172.13E−04 0.00048 0.00087 0.00361 9 10 11 12 13 14 15 16 K 0 0 0−36.08796 1.91E−09 0 −13.89285 −6.56564 A −0.00617 −0.00438 0.020520.06176 0.03212 0.01767 −0.0928 −0.03629 B −0.00696 −0.01767 −0.03901−0.05279 −0.02053  −0.00785 0.02768  0.01032 C −0.01576 0.01024 0.018870.01978 0.00343 0.00239 −0.00608 −0.00215 D 0.04758 0.00136 −0.0054−0.00432 0.00041 −0.00049 0.00092  0.00029 E −0.05539 −0.00466 0.000890.00059 −0.00024  6.63E−05 −6.99E−05  −2.63E−05 F 0.03571 0.00264−0.00007 −0.00005 3.71E−05 −5.65E−06  3.69E−07  1.51E−06 G −0.01315−0.00072 0 2.98E−06 −2.91E−06  2.90E−07 3.18E−07 −5.32E−08 H 0.002589.69E−05 1.39E−06 −9.73E−08  1.16E−07 −8.20E−09  −2.00E−08   1.02E−09 I−0.00021 −5.19E−06  −8.35E−08  1.40E−09 −1.88E−09  9.76E−11 3.82E−10−8.14E−12

The imaging optical system of FIG. 5 may have the aberrationcharacteristics illustrated in FIG. 6.

An optical imaging system according to a fourth example is hereinafterdescribed with reference to FIGS. 7 and 8.

The optical imaging system according to the fourth example may include afirst lens 410, a second lens 420, a third lens 430, a fourth lens 440,a fifth lens 450, a sixth lens 460, a seventh lens 470, and an eighthlens 480, and may further include a stop ST, a filter 490, and an imagesensor 491.

Lens characteristics (radii of curvature, thicknesses of lenses ordistances between the lenses, refractive indices, Abbe numbers, andfocal lengths) of each lens are shown in Table 7.

TABLE 7 Surface Radius of Thickness/ Refractive Abbe Focal No. Ref.Curvature Distance Index Number Length 1 First Lens 5.75991 0.260441.5441 56.1 −55.377 2 Stop 4.76163 0.02484 3 Second Lens 3.19783 0.632581.5441 56.1 6.608 4 25.99389 0.24946 5 Third Lens 6.18054 0.5746 1.544156.1 8.146 6 −15.39273 0.02484 7 Fourth Lens 10.68026 0.25425 1.6573921.5 −8.331 8 3.58622 0.44592 9 Fifth Lens −24.07628 0.59387 1.6890218.4 249.907 10 −21.33535 0.51446 11 Sixth Lens 5.20519 0.5464 1.544156.1 32.483 12 7.09146 0.32327 13 Seventh Lens 72.67215 0.83559 1.544156.1 10.818 14 −6.40939 0.3946 15 Eighth Lens 12.76799 0.71139 1.536655.6 −4.584 16 2.02247 0.31044 17 Filter Infinity 0.11 18 Infinity 0.6219 Image Infinity Capturing Surface

According to the fourth example, an overall focal length of the opticalimaging system f is 5.86 mm, Fno is 1.82, BFL is 1.04 mm, FOV is 80.5°,and IMG HT is 4.7 mm.

Fno is the number indicating the brightness of the optical imagingsystem, BFL is a distance from an image-side surface of the eighth lensto the image capturing surface of the image sensor, FOV is a field ofview of the optical imaging system, and IMG HT is half of a diagonallength of the image capturing surface of the image sensor.

In the fourth example, the first lens 410 may have negative refractivepower, and a first surface of the first lens 410 may be convex and asecond surface of the first lens 410 may be concave.

The second lens 420 may have positive refractive power, and a firstsurface of the second lens 420 may be convex and a second surface of thesecond lens 420 may be concave.

The third lens 430 may have positive refractive power, and the first andsecond surfaces of the third lens 430 are convex.

The fourth lens 440 may have negative refractive power, and a firstsurface of the fourth lens 440 may be convex and a second surface of thefourth lens 440 may be concave.

The fifth lens 450 may have positive refractive power, and a firstsurface of the fifth lens 450 may be concave and a second surface of thefifth lens 450 may be convex.

The sixth lens 460 may have positive refractive power, and a firstsurface of the sixth lens 460 may be convex in a paraxial area and asecond surface of the sixth lens 460 may be concave in the paraxialarea.

At least one inflection point may be formed on at least one of the firstand second surfaces of the sixth lens 460. For example, the firstsurface of the sixth lens 460 may be convex in a paraxial region andbecome concave toward an edge thereof. The second surface of the sixthlens 460 may be concave in a paraxial region and become convex toward anedge thereof.

The seventh lens 470 may have positive refractive power, and the firstand second surfaces of the seventh lens 470 are convex in a paraxialarea.

At least one inflection point may be formed on at least one of the firstand second surfaces of the seventh lens 470. For example, the firstsurface of the seventh lens 470 may be convex in a paraxial region andbecome concave toward an edge thereof.

The eighth lens 480 may have negative refractive power, and a firstsurface of the eighth lens 480 may be convex in a paraxial area and asecond surface of the eighth lens 480 may be concave in the paraxialarea.

At least one inflection point may be formed on at least one of the firstand second surfaces of the eighth lens 480. For example, the firstsurface of the eighth lens 480 may be convex in a paraxial region andbecome concave toward an edge thereof. The second surface of the eighthlens 480 may be concave in a paraxial region and become convex toward anedge thereof.

Respective surfaces of the first to eighth lenses 410 to 480 may haveaspherical coefficients as illustrated in Table 8. For example, all ofobject-side surfaces and image-side surfaces of the first to eighthlenses 410 to 480 may be aspherical.

The stop ST may be disposed between the first lens 410 and the secondlens 420.

TABLE 8 1 2 3 4 5 6 7 8 K −3.08543 −2.8028 −0.07196 −51.46079 −0.14708−5.29575 43.785 −7.18081 A −0.00896 0.02702 0.03331 −0.00605 −0.00493−0.03019 −0.04948 0.01191 B −0.01088 −0.08985 −0.09038 −0.01711 −0.001540.03685 0.04692 −0.06665 C 0.01038 0.09881 0.10145 0.04512 0.017440.04338 0.03739 0.23648 D −0.00321 −0.05398 −0.06185 −0.0696 −0.03721−0.17617 −0.17361 −0.43457 E −0.00018 0.01674 0.02254 0.06467 0.041780.21221 0.2253 0.49426 F 0.00036 −0.0031 −0.00506 −0.03586 −0.02795−0.13701 −0.15814 −0.35382 G −9.51E−05 0.00034 0.00068 0.01157 0.010780.05081 0.06435 0.15502 H  1.08E−05 −2.04E−05  −5.13E−05 −0.00197−0.00217 −0.01016 −0.01423 −0.03792 I −4.76E−07 5.17E−07 0 0.000141.75E−04 0.00085 0.00132 0.00396 9 10 11 12 13 14 15 16 K 0.00009−0.0001 −0.00001 −36.08705 −1.18E−05 −0.0003 −13.89436 −6.56558 A−0.00608 −0.00471 0.0202 0.06225 0.03201 0.01654 −0.09337 −0.03603 B−0.00747 −0.01658 −0.03844 −0.05331 −0.02025  −0.00698 0.02877 0.0104 C−0.01422 0.00898 0.01826 0.02002 0.00325 0.0021 −0.00686 −0.00223 D0.04541 0.00223 −0.00496 −0.00438 0.00047 −0.00044 0.00121  0.00031 E−0.05406 −0.00511 0.0007 0.0006 −0.00025  6.09E−05 −1.31E−04 −2.83E−05 F0.03548 0.00282 −0.00002 −0.00005  3.82E−05 −5.29E−06   8.17E−06 1.64E−06 G −0.01327 −0.00077 −0.00001 3.04E−06 −2.98E−06 2.76E−07−2.73E−07 −5.82E−08 H 0.00263 1.04E−04 2.06E−06 −9.95E−08   1.19E−07−7.88E−09   4.61E−09  1.13E−09 I −0.00022 −5.60E−06  −1.07E−07  1.43E−09−1.91E−09 9.44E−11 −4.89E−11 −9.02E−12

The imaging optical system of FIG. 7 may have the aberrationcharacteristics illustrated in FIG. 8.

An optical imaging system according to a fifth example is hereinafterdescribed with reference to FIGS. 9 and 10.

The optical imaging system according to the fifth example may include afirst lens 510, a second lens 520, a third lens 530, a fourth lens 540,a fifth lens 550, a sixth lens 560, a seventh lens 570, and an eighthlens 580, and may further include a stop ST, a filter 590, and an imagesensor 591.

Lens characteristics (radii of curvature, thicknesses of lenses ordistances between the lenses, refractive indices, Abbe numbers, andfocal lengths) of each lens are shown in Table 9.

TABLE 9 Surface Radius of Thickness/ Refractive Abbe Focal No. Ref.Curvature Distance Index Number Length 1 First Lens 2.40122 0.911781.5441 56.1 5.258 2 Stop 12.71987 0.15391 3 Second Lens 16.77065 0.343181.68902 18.4 −13.935 4 6.04338 0.35614 5 Third Lens 10.6895 0.64811.5441 56.1 32.58 6 26.21561 0.31987 7 Fourth Lens 16.69219 0.33091.67694 19.2 −39.387 8 10.18336 0.34682 9 Fifth Lens −8.2382 0.7 1.544156.1 4.927 10 −2.0887 0.12023 11 Sixth Lens −11.50963 0.47767 1.6769419.2 41.736 12 −8.31509 0.04069 13 Seventh Lens −8.70619 0.54675 1.544156.1 −30.274 14 −18.80498 0.3748 15 Eighth Lens −8.4635 0.32232 1.544156.1 −3.748 16 2.73471 0.17694 17 Filter Infinity 0.21 18 Infinity 0.7119 Image Infinity Capturing Surface

According to the fifth example, an overall focal length of the opticalimaging system f is 5.69 mm, Fno is 1.74, BFL is 1.09 mm, FOV is 80.5°,and IMG HT is 4.7 mm.

Fno is the number indicating the brightness of the optical imagingsystem, BFL is a distance from an image-side surface of the eighth lensto the image capturing surface of the image sensor, FOV is a field ofview of the optical imaging system, and IMG HT is half of a diagonallength of the image capturing surface of the image sensor.

In the fifth example, the first lens 510 may have positive refractivepower, and a first surface of the first lens 510 may be convex and asecond surface of the first lens 510 may be concave.

The second lens 520 may have negative refractive power, and a firstsurface of the second lens 520 may be convex and a second surface of thesecond lens 520 may be concave.

The third lens 530 may have positive refractive power, and a firstsurface of the third lens 530 may be convex in a paraxial area and asecond surface of the third lens 530 may be concave in the paraxialarea.

At least one inflection point may be formed on at least one of the firstand second surfaces of the third lens 530. For example, the firstsurface of the third lens 530 may be convex in a paraxial region andbecome concave toward an edge thereof.

The fourth lens 540 may have negative refractive power, and a firstsurface of the fourth lens 540 may be convex in a paraxial area and asecond surface of the fourth lens 540 may be concave in the paraxialarea.

At least one inflection point may be formed on at least one of the firstand second surfaces of the fourth lens 540. For example, the firstsurface of the fourth lens 540 may be convex in a paraxial region andbecome concave toward an edge thereof. The second surface of the fourthlens 540 may be concave in a paraxial region and become convex toward anedge thereof.

The fifth lens 550 may have positive refractive power, and a firstsurface of the fifth lens 550 may be concave and a second surface of thefifth lens 550 may be convex.

The sixth lens 560 may have positive refractive power, and a firstsurface of the sixth lens 560 may be concave in a paraxial area and asecond surface of the sixth lens 560 may be convex in the paraxial area.

At least one inflection point may be formed on at least one of the firstand second surfaces of the sixth lens 560. For example, the firstsurface of the sixth lens 560 may be concave in a paraxial region andbecome convex toward an edge thereof.

The seventh lens 570 may have negative refractive power, and a firstsurface of the seventh lens 570 may be concave in a paraxial area and asecond surface of the seventh lens 570 may be convex in the paraxialarea.

The eighth lens 580 may have negative refractive power, and the firstand second surfaces of the eighth lens 580 are concave in a paraxialarea.

At least one inflection point may be formed on at least one of the firstand second surfaces of the eighth lens 580. For example, the firstsurface of the eighth lens 580 may be concave in a paraxial region andbecome convex toward an edge thereof. The second surface of the eighthlens 580 may be concave in a paraxial region and become convex toward anedge thereof.

Respective surfaces of the first to eighth lenses 510 to 580 may haveaspherical coefficients as illustrated in Table 10. For example, all ofobject-side surfaces and image-side surfaces of the first to eighthlenses 510 to 580 may be aspherical.

The stop ST may be disposed between the first lens 510 and the secondlens 520.

TABLE 10 1 2 3 4 5 6 7 8 K −1.0619 10.65292 −4.74332 −8.63393 −24.14491−8.12023 37.95587 −25.39721 A 0.00763 −0.0189 −0.0392 −0.02606 −0.03097−0.03786 −0.1034 −0.08478 B 0.0099 0.01067 0.04699 0.02019 0.015830.02381 0.08748 0.05695 C −0.02019 0.00237 −0.06599 0.00943 −0.06117−0.04896 −0.18249 −0.09928 D 0.02665 −0.01481 0.09808 −0.04998 0.114960.05954 0.25179 0.11249 E −0.02144 0.01613 −0.10515 0.07734 −0.13884−0.05098 −0.21683 −0.07793 F 0.01058 −0.00945 0.07228 −0.06816 0.10330.02801 0.11502 0.03357 G −3.13E−03 0.00312 −0.03011 0.03586 −0.04584−0.0093 −0.03661 −0.00877 H  5.02E−04 −5.36E−04  6.94E−03 −0.0104 0.01110.00171 0.00644 0.00127 I −3.39E−05 3.67E−05 −0.00068 0.00129 −1.12E−03−0.00014 −0.00049 −0.00008 9 10 11 12 13 14 15 16 K −27.60605 −1.21271−3.65879 3.2172 3.22E+00 −36.17655 −99 −1.14208 A −0.0176 0.034780.01282 0.04791 0.0871 0.05673 −0.04929 −0.09202 B 0.02288 −0.02336−0.0205 −0.03595 −0.06966 −0.04938 −0.00565 0.02815 C −0.05095 0.006810.01218 0.01233  0.02316 0.01964 0.01242 −0.00577 D 0.0445 −0.00207−0.00585 −0.00264 −0.00428 −0.00433 −0.00407 0.00079 E −0.0223 0.000960.00167 0.00036  0.00047 5.64E−04 6.52E−04 −7.29E−05 F 0.00714 −0.00026−0.00027 −0.00003 −2.97E−05  −4.44E−05  −5.97E−05   4.42E−06 G −0.001470.00004 0.00002 1.27E−06 9.98E−07 2.08E−06 3.19E−06 −1.69E−07 H 0.00018−2.41E−06  −1.15E−06  −2.30E−08  −1.35E−08  −5.30E−08  −9.28E−08  3.67E−09 I −0.00001 6.22E−08 2.27E−08 0.00E+00 0.00E+00 5.62E−101.14E−09 −3.47E−11

The imaging optical system of FIG. 9 may have the aberrationcharacteristics illustrated in FIG. 10.

As set forth above, according to various examples, due to an opticalimaging system, an aberration improvement effect may be improved, whilehigh resolution may be implemented.

While this disclosure includes specific examples, it will be apparent toone of ordinary skill in the art that various changes in form anddetails may be made in these examples without departing from the spiritand scope of the claims and their equivalents. The examples describedherein are to be considered in a descriptive sense only, and not forpurposes of limitation. Descriptions of features or aspects in eachexample are to be considered as being applicable to similar features oraspects in other examples. Suitable results may be achieved if thedescribed techniques are performed to have a different order, and/or ifcomponents in a described system, architecture, device, or circuit arecombined in a different manner, and/or replaced or supplemented by othercomponents or their equivalents. Therefore, the scope of the disclosureis defined not by the detailed description, but by the claims and theirequivalents, and all variations within the scope of the claims and theirequivalents are to be construed as being included in the disclosure.

What is claimed is:
 1. An optical imaging system, comprising: a firstlens, a second lens, a third lens, a fourth lens, a fifth lens, a sixthlens, a seventh lens, and an eighth lens sequentially arranged from anobject side of the optical imaging system, wherein a refractive index ofat least one of the lenses is 1.67 or greater.
 2. The optical imagingsystem of claim 1, wherein FOV>70°, where FOV is a field of view of animaging system including the first lens to the eighth lens.
 3. Theoptical imaging system of claim 1, wherein f/EPD<1.9, where f is anoverall focal length of an imaging system including the first lens tothe eighth lens, and EPD is a diameter of an entrance pupil.
 4. Theoptical imaging system of claim 1, wherein the first lens has positiverefractive power, the second lens has positive refractive power, and thethird lens has positive refractive power.
 5. The optical imaging systemof claim 4, wherein the fourth lens has negative refractive power, thefifth lens has positive refractive power, the sixth lens has negativerefractive power, the seventh lens has positive refractive power, andthe eighth lens has negative refractive power.
 6. The optical imagingsystem of claim 1, wherein the first lens has negative refractive power,the second lens has positive refractive power, and the third lens haspositive refractive power.
 7. The optical imaging system of claim 6,wherein the fourth lens has negative refractive power, the fifth lenshas positive refractive power, the sixth lens has positive refractivepower, the seventh lens has positive refractive power, and the eighthlens has negative refractive power.
 8. The optical imaging system ofclaim 1, wherein the first lens has positive refractive power, thesecond lens has negative refractive power, and the third lens haspositive refractive power.
 9. The optical imaging system of claim 8,wherein the fourth lens has negative refractive power, the fifth lenshas positive refractive power, the sixth lens has positive refractivepower, the seventh lens has negative refractive power, and the eighthlens has negative refractive power.
 10. The optical imaging system ofclaim 1, further comprising a stop disposed between the first lens andthe second lens.
 11. The optical imaging system of claim 1, wherein,among the lenses, an absolute value of a focal length of the eighth lensis the lowest.
 12. The optical imaging system of claim 1, wherein atleast one of the lenses has positive refractive power with a refractiveindex of 1.67 or greater, and at least one of the lenses has negativerefractive power with a refractive index of 1.65 or greater.
 13. Anoptical imaging system, comprising: a first lens, a second lens, a thirdlens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and aneighth lens sequentially arranged from an object side of the opticalimaging system, wherein an object-side surface of the first lens isconvex, and an image-side surface of the first lens is concave, arefractive index of at least one of the lenses is 1.67 or greater, andFno<1.9, where Fno is an F-number of an imaging system including thefirst lens to the eighth lens.
 14. The optical imaging system of claim13, wherein at least one of the lenses has positive refractive powerwith a refractive index of 1.67 or greater, and at least one of thelenses has negative refractive power with a refractive index of 1.65 orgreater.
 15. The optical imaging system of claim 13, wherein FOV>70°,where FOV is a field of view of an imaging system including the firstlens to the eighth lens.
 16. The optical imaging system of claim 13,wherein TTL/(2*IMG HT)<0.9, where TTL is an optical axis distance fromthe object-side surface of the first lens to an image capturing surfaceof an image sensor, and IMG HT is half of a diagonal length of the imagecapturing surface of the image sensor.
 17. An optical imaging system,comprising: a first lens, a second lens, a third lens, a fourth lens, afifth lens, a sixth lens, a seventh lens, and an eighth lenssequentially arranged from an object side of the optical imaging system,wherein f/EPD<1.9, where f is an overall focal length of an imagingsystem including the first lens to the eighth lens and EPD is a diameterof an entrance pupil.
 18. The optical imaging system of claim 13,wherein at least four of the lenses have positive refractive power.